E-Mail IMAGE: New research from Washington University in St. Louis in the journal eLife shows how animals and bacteria differ in the enzyme they use to attach heme to the cytochrome. Spotting... view more Credit: (Courtesy of Robert Kranz) It took an unlikely food innovation -- earth-friendly vegetarian patties, made to taste and "bleed" like the familiar meaty ones -- to make people aware of heme. But heme is an essential part of proteins found in most life forms, from tiny bacteria to soy plants to the human body. Heme plays a crucial role in supplying cells with the energy needed to carry out chemical reactions.